RTLS systems estimate locations for moving tags or moving personnel badges within a floor plan of interior rooms, in buildings such as hospitals. Many RTLS systems based on radio-frequency signals such as Wi-Fi or Bluetooth Low Energy (BLE), are designed to have moving tags that transmit a radio signal, within a field of receiving devices called bridges, gateways, sensors, or Access Points. A network of bridges will measure and use received signal strength of transmissions from a tag, as a proxy for estimating the distance between the tag and each bridge, and then use multi-lateration algorithms to estimate the locations of tags. Those approaches with tags that transmit are standard in the industry and provide location estimates that are acceptable for may use cases in industrial and manufacturing environments. They may even be accurate enough to locate tagged assets and tagged people with accuracy within 1-meter or less. But the approaches common in the industry fail to provide an efficient location system for determining the precise location of a tag at bay-level or bed-level in large, open patient-care areas in hospitals, or in a hospital room with two patient beds.
Hospitals typically have several, large, patient-care rooms where may patients can be treated simultaneously, such as an ED receiving room, a prepare-for-surgery room, a recovery-from-surgery room, or an infusion room. These large rooms are designed with a set of small bays, where each bay is defined as a treatment area for one patient. Each bay usually has enough floor space to hold one bed, and/or one chair, for a patient to lie in or sit in. The bays may be separated by a curtain. The curtain may be suspended from a track in the ceiling of the bay, which allows a curtain to be drawn or retracted to provide a private space for the patient's care. The bays may alternatively be divided by a structural half-wall or other privacy structure.
Hospitals also have patient rooms for inpatients which are shared by two or more patients in two or more beds. The beds in these shared multi-patient rooms are typically separated by a curtain.
RTLS systems in hospitals in common use may be able to determine or estimate the location of tagged assets, patients and staff members at a room level or with 1-meter accuracy, but RTLS systems in common use fail to determine reliably which bay the tag resides in. For example, the common RTLS system struggles to determine which side of the curtain a tag resides on. A better location system is required that can reliably determine which side of a curtain a tag resides on, so the hospital can determine which bay a patient is seated in, and which caregivers are in the bay with the patient, and determine which assets are in the bay with the patient. Similarly, RTLS systems in common use fail to determine which bed a tag resides on or near, in a multi-patient room.
To illustrate the accuracy problem, imagine a hospital patient-care area that is a large room, hosting many patients, divided into bays. Patients may sit in beds or lie or chairs just 1 meter apart from each other, separated by a curtain. For some hospital use cases, an RTLS system must be accurate enough to determine which bed, chair or bay a patient is located in, and also determine which pieces of medical equipment are in the same bay with that patient, and also determine which staff members are in the same bay with that patient. An RTLS system that uses radio-signals may be able to estimate a location for a patient, asset or staff member within 1-meter accuracy, but still struggle to answer the question of precisely which side of the curtain the tagged asset, patient or staff member is on because the patients are only 1 meter apart. RTLS systems have used infrared light or ultrasound signals to build “virtual walls” where the curtains separate the bays, but these systems require significant design, engineering, tuning, and cost.
The current invention proposes a novel use of a bay-level event sensor. A bay-level event sensor is defined as an electronic sensing device that can determine whether an event occurs in one bay, or its adjacent bay. In one embodiment of the invention, a bay-level event sensor may be a fixed thermographic camera, and the bay-level event it senses is motion in the bay, of an object that appears to be the size and shape of a human person. The fixed camera can sense motion in one bay, without sensing motion in any nearby bay. Or the camera can sense multiple bays, and through analysis of one or more camera images, determine which bay an event is occurring in. In another embodiment, a bay-level event sensor may be a pressure sensor on a bed or chair. The bay-level event it senses is the action of a person sitting down or rising from a bed or chair. The bay-level pressure sensor can determine whether a person is sitting in a chair or bed in a precise bay, without sensing a person sitting in any adjacent bay.
The event that each bay-level event sensor detects, occurring in a specific bay but not an adjacent bay, is generally defined as a motion event. A bay-level thermo-graphic camera may detect a human body moving in a specific bay, or a rolling equipment cart moving in a specific bay. A bay-level pressure sensor may detect a person seated in a bed or chair in a specific bay, or a motion event of a person sitting down into a chair or bed, or a motion event of a person standing up from a seated position in a chair or bed.
Estimating the location of a tag with a precision of determining which bay a tag resides in is often named “bay-level accuracy”. If there is one bed in that one bay, then the bay-level accuracy may be referred to as “bed-level accuracy”. If there is one chair in that one bay, then the bay-level accuracy may be referred to as “chair-level accuracy”.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.